School of Physics , University College Dublin , Dublin 4 , Ireland.
Center for Nanophase Materials Science , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37830 , United States.
ACS Appl Mater Interfaces. 2018 Aug 29;10(34):29153-29160. doi: 10.1021/acsami.8b09513. Epub 2018 Aug 14.
Polarization switching in ferroelectric materials underpins a multitude of applications ranging from nonvolatile memories to data storage to ferroelectric lithography. While traditionally considered to be a functionality of the material only, basic theoretical considerations suggest that switching is expected to be intrinsically linked to changes in the electrochemical state of the surface. Hence, the properties and dynamics of the screening charges can affect or control the switching dynamics. Despite being recognized for over 50 years, analysis of these phenomena remained largely speculative. Here, we explore polarization switching on the prototypical LiNbO surface using the combination of contact mode Kelvin probe force microscopy and chemical imaging by time-of-flight mass-spectrometry and demonstrate pronounced chemical differences between the domains. These studies provide a consistent explanation to the anomalous polarization and surface charge behavior observed in LiNbO and point to new opportunities in chemical control of polarization dynamics in thin films and crystals via control of surface chemistry, complementing traditional routes via bulk doping, and substrate-induced strain and tilt systems.
铁电材料中的极化反转支撑着众多应用，从非易失性存储器到数据存储再到铁电光刻。虽然传统上认为这只是材料的一种功能，但基本理论考虑表明，反转应该与表面电化学状态的变化内在相关。因此，屏蔽电荷的性质和动力学可以影响或控制反转动力学。尽管这一现象已经被认识了 50 多年，但对这些现象的分析在很大程度上仍然是推测性的。在这里，我们使用接触模式 Kelvin 探针力显微镜和飞行时间质谱化学成像相结合，研究了原型 LiNbO 表面的极化反转，并证明了畴之间存在明显的化学差异。这些研究为 LiNbO 中观察到的异常极化和表面电荷行为提供了一致的解释，并为通过控制表面化学来控制薄膜和晶体中极化动力学提供了新的机会，这补充了通过体掺杂、基于衬底的应变和倾斜系统来控制极化动力学的传统方法。
